Apparatus for automatically controlling drilling



Ap 1962 A. l. ROBINSON ETAL 3,031,169

APPARATUS FOR AUTOMATICALLY CONTROLLING DRILLING- Filed July 6. 1959 3 Sheets-Sheet 1 f w? a //a //A I Arr Rob/0:017 Gar/nan 0. Amvme/l 2.9 2a 25a j fig i p I BY ,5. im la AT r ORA/E KS A nl 24, 1962 A. ROBINSON ETAL 3,031,169

APPARATUS 0R AUTOMATICALLY CUNTROLLING DRILLING Filed July 6, 1959 3 Sheets-Sheet 2 Art 1. Rab/n30) Gar/77a 0. Almmefl INVENTORS 75 H '79 BY A re Ne w April 24, 1962 A. l. ROBINSON ETAL 3,031,169

APPARATUS FOR AUTOMATICALLY CONTROLLING DRILLING Filed July 6. 1959 s Sheets-Sheet :5

1-50 I I3] M2 5 WV 263 14H 1. fialnJon' German 0. /(/mme// INVENTORS W BY EEIZyMl/J United States Patflfg 3,031,169 APPARATUS FOR AUTOMATICALLY CONTROLLING DRILLING Art L Robinson, Wichita Falls, Tax, and Garnran 0.

Kimmell, Oklahoma City, Okla., assignors to Bear Corporation, Wichita Falls, Ten, a corporation exas Filed July 6, 1959, Ser. No. 824,976

12 Claims. (CL 254-173) This invention relates to new and useful improvements is responsive to tension in the drill string cable system,

in methods of and apparatus for automatically controlling drilling of well bores.

The invention relates particularly to controlling the weight on the drilling bit during a well bore drilling operation.

Various methods and apparatus have been in use for automatically controlling weight on-bit, but such prior methods and apparatus have disadvantages which are overcome by the present invention. For example, certain of the prior arrangements are complicated in construction and require extensive drawworks modifications, while others may demand extra manipulation during the drilling operation. Also, attempts have been made to control weight-on-bit by automatically controlling the usual brake lever of the drawworks; however, because of the inherent action of the usual brake system, difficulty has been experienced in maintaining. proper control within a satisfactory range, with the result that the weighton-bit is not accurately maintained within desired limits.

It is, therefore, one object of this invention to provide an improved apparatus for automatically controlling the weight-on-bit which may be applied to the usual brake of the drawworks cable drum and which provides accurate control with smooth and responsive operation.

An important object is to provide an improved drilling controldevice which is automatically responsive to the tension in the cable system supporting the drill pipe and bit and which device actuates the usual brake of the drawworks drum to control the weight on said bit during the dr lling operation; the apparatus including an auxiliary control unit which feeds back intelligence to the main tained within the desired or satisfactory range.

Still another object is to provide an apparatus of the character described which employs a pneumatic weighton-bit control system having incorporated therein an auxiliary control unit, which auxiliary unit functions to counteract the normal tendency of the main control system to overcontrol, whereby the inherent disadvantages of the main system are overcome and sensitive control of the weight-on-bit is accomplished.

A further object is to provide an apparatus, of the character described, which is readily portable and may be easily applied to any standard drilling rig without major or extensive modification of said rig; said apparatus including an auxiliary control device which not only renders the apparatus more efficient under normal operation but which, without additional manipulation, functions as a safety device which prevents the drill string against sudden falling dueto encountering an enlargement or cavern in the bore or for other reasons.

Still another object is to provide an apparatus, of the character described, which may be readily adjusted to assure proper weight-on-bit control at any rate of drilling, that is, the apparatus will permit a maximum drilling rate and yet will effectively control weight-on-bit under slow drilling conditions.

A particular object is to provide an improved method of controlling weight-on-bit by applying a force, which to the braking mechanism of the cable drum to feed said cable fromthe drum in accordance with said tension and immediatelyrelieving-a portion of the applied force as soon as said cable drum moves as a result of the application of force, {whereby substantially instantaneously followingthe motion of the drum the applied force is reduced and its effect counteracted to provide for a smooth, restaonsive operation and accurate control of the weightonit.

The construction designed to carry out the invention will be hereinafter described, together with other features thereof.

The invention will be more readily understood from a. reading of the following specification and by reference to the accompanying drawings forming a part thereof, wherein an example of the invention is shown and wherein:

FIGURE 1 is a diagrammatic view of a drilling control apparatus, constructed in accordance with the invention and illustrating the same applied to the cable drum and the cable system which supports the usual drill pipe or string;

FIGURE 2 is an isometric view of the auxiliary control unit which feeds back intelligence from the cable drum to the main pneumatic actuating system;

FIGURE 3 is a longitudinal sectional view of the auxcontrol unit and illustrating the operating shaft and the valve means thereof;

FIGURE 4 is an isometric view of the valve disk and valve block of the valve means of the auxiliary control unit;

FIGURE 5 is a partial sectional view illustrating a modified form of valve means which may be employed in the auxiliary control unit;

FIGURE 6 is an enlarged sectional view of a modified type of difierential pilot device which may be employed in lieu of the differential pilot device illustrated in FIG- URE 1;

FIGURE 7 is a diagrammatic view illustrating a hydraulic pump which may be employed in place of the control unit illustrated in FIGURES 1-4.

FIGURE 8 is a schematic diagram of a modified form of the invention wherein the auxiliary control unit is located at'a point remote from the cable drum, and

FIGURE 9 is a partial diagrammatic view of a portion of the drilling control apparatus and showing an alternate connection between the auxiliary control unit E and the motor device or actuator D.

In the drawings (FIGURE 1) the numeral 10 designates the usual crown block which is mounted in the upper end of a well derrick (not shown), and suspended from said crown block by means of .a cable system, generally indicated at 11, is a traveling block 12. A kelly 13 is suspended from a swivel 14 carried by the traveling block 12, and connected to the lower end of the kelly is a drill string 15 having a drilling bit 16 at its lower end. The drill string and bit extend downwardly within the well bore W, and as the string and bit are rotated said bore is drilled in the well known manner. The kelly 13 extends through and is rotated by a rotary table 17 on the floor 18 of the rig, said rotary table functioning to impart rotation to the drill string and bit to perform the drilling other end of the cable forming the cable system is connected to a cable supply drum or drawworks drum 20 which is mounted on the derrick floor. The section 11b between the cable or drawworks drum 20 and the crown block is generally known as a fast line since it is the fastest moving section of the cablesystem.

The cable drum 20 is operated by suitable power equipment (not shown) for rotating said drum in a direction to reel in cable when it is desired to raise the traveling block 12 and the drill string 15. When the drum is rotated in an opposite direction, cable is payed out from the cable drum into the fast line section 11b of the system. The drum rotates in a direction to pay out cable by the release of a suitable braking means which is controlled by a brake lever 21. As is obvious, the weight of the drill string suspended from the cable system is constantly applied to said cable system and when the braking means is released, this weight efiects a rotation of the drum in a direction to pay out cable. A coil spring 22, having one end attached to the brake lever and its other end attached to a fixed point 23, normally holds the brake lever in a position applying suflicient braking action to the drum 20 to prevent rotation of said drum. By moving the brake lever 21 against tension of the spring, the brake may be released to allow the desired pay out of cable from the drum 20.

During the actual drilling operation it is necessary to apply at least part of the weight of the drill string 15 to the bit 16 to secure proper penetration of the formation. As is well known, different formations require ditferent weights-on-bit. Improper weight-on-bit can result in crooked holes, balling up of cuttings, damage to drill pipe, sticking of drill pipe and other difficulties. Thus, weighton-bit is a controlling factor in efiicient well bore drilling.

As the bit 16 drills downwardly it is required that cable be payed out from the drum 20 into the fast line section 11b of the cable system 11 in order to maintain 'the desired weight on the bit. This paying out of cable is accomplished bymoving the brake lever 21 against the tension of the spring 22, which results in releasing the braking means which is acting upon the drum 20. It is the purpose of the present invention to provide a smooth and responsive control apparatus for performing this function automatically so as to maintain the desired weight-onbit throughout the drilling of the well.

Referring to FIGURE 1 which illustrates one form of the present invention, the improved apparatus includes a tension responsive means or load indicator A which is located on the deadline 11a and which is responsive to tension in the cable system 11. The tension in the cable system including the deadline is inversely related to the weight applied to the bit 16 for a given length of the drill string 15, and the variations in tension in said cable system are utilized to control operation of the tension responsive means A. As will be explained in detail hereinafter, tension responsive unit A directs a pressure signal to a differential pilot control device B. The pilot control device B presents a predetermined or selected resistance to the pressure signal, and when said device operates it modulates a pilot or control pressure which is directed through a line 24 connecting said device B to a typical pneumatic multiplier unit C. The pressure in line 24, by reason of the control device B, is modulated in accordance with the signal transmitted to device B by the tension responsive unit A, and, therefore, the modulated pressure which is directed to the multiplier unit C is proportional to or representative of the tension in the deadline 11a.

The multiplier unit C has connection through a conductor 25 with a diaphragm motor device or actuator D of well known construction whereby the actuator may be energized or tie-energized. Such device includes a diaphragm 26 formed with an actuating stem 27 having its lower end pivotally connected at 28 to an operating arm 29 which has one end pivoted to a fixed bracket 29a. Upon downward movement of the stem 27, arm 29 is moved in accordance with the p eset"? acting P um diaphragm 26 of the actuator device D. The outer end of the operating arm 29 has one end of an actuating cable 30 secured thereto, and this cable extends upwardly over idlers 31 and then extends downwardly to be secured at 32 to the outer end of the brake control lever 21, whereby the brake control lever is moved in accordance with movement of operating arm 29.

From the foregoing it will be seen that the tension responsive means A, pilot control device, actuator device D with the associated conductors comprising a main control or actuating system for controlling the braking force on the drum 20. The pressure signal from the unit A, which is representative of tension in'the cable system, is utilized to energize and de-energize the actuator device D to control the movement of the brake lever. When the brake lever 21 is swung upwardly, the braking force acting upon the drum 20 is reduced, thereby permitting a rotation of the drum 20 so that cable is payed out into the fast line section 11b of the cable system.

Attempts have been made to employ this general type of system for automatically controlling the brake lever 21 of the cable drum. However, when the brake lever 21 is moved to permit rotation of the drum, the cable will pay out as soon as the drum starts rotating. As the cable pays out, the tension in the cable system immediately changes and this results in unit A sending a changed signal to the pilot control device B. This changed signal in accordance with the new conditions, of course, produces a different pressure on the motor device or actuator D and ultimately results in tending to move the arm 29 and cable 30 in a direction to again apply more braking action. However, because of the hysteresis throughout the system, there is a lag between the time that the unit A can react to the changed conditions and send its signal and the time that the brake lever 21 is returned toward a fully braked position. Such lag results in paying out too much cable from the drum 20 with the result that the desired weighton-bit is not maintained. The inherent lag in a control system of this type makes it impossible to accurately control weight-on-bit within a close range.

In order to overcome the inherent disadvantages of paying out more cable than is required upon each operation of the apparatus, an auxiliary control unit generally indicated at E is provided. This unit, as will be explained, is responsive to the rotation of the drum 20 and is therefore responsive to cable payout and has connection with the main control or actuating system to feed back intelligence to such system. In the form shown in FIGURE 1, the auxiliary control unit E includes a valve means V which has connection through a line 33 with the pressure line 24 which extends between pilot control device B and the multiplier unit C. As will be explained, the valve means V is arranged to vent or release part of the pilot or control pressure from line 24 the instant that the drum 20 starts rotating as a result of actuation of the brake lever 21. Therefore, as soon as brake lever 21 is moved in a direction to reduce the braking action on drum 20 and said drum starts rotating to feed out cable, the unit E is actuated to vary the pressure which is acting upon the actuator device D to partially de-energize the main control or actuating system. By immediately or substantially immediately changing the pressure acting upon the device D to partially de-energize the system, said device reacts to permit the brake lever 21 to return toward a more fully braking position. The unit E thus counteracts substantially immediately the action of the device D, with the result that as soon as the brake 21 is moved by the device D to start paying out cable, the auxiliary control unit is operated, and its operation results in returning the brake lever 21 to more fully braking position. The ultimate effect is that an excessive pay out of-cable into the system is not possible, and the weight-on-bit may be maintained within very close limits.

Considering the invention in more detail, the tension responsive means A may be of any suitable type and is,

therefore, shown only diagrammatically. For example, it may be of the type shown in the prior patent to Shimek 2,013,810. A supply pressure is conducted to the unit A through a line 34, and as tension in the cable system varies a pressure signal is conducted through a line 35 to the diflerential pilot cgntrolB. The pressure signal transmitted from the unit A to the device B is proportional to the tension in the deadline 11a and is thus inversely related to the weight on the drill bit 16 for a given length of drill string.

The pilot control device B is clearly shown in FIG- URE 1 and includes a main housing 36. One end of the housing has an end member 37 secured thereto, while the opposite end of the housing is closed by a dome or bonnet 38. A double diaphragm assembly is located within the housing 36 and includes a centralsupport 39 having an enlarged diaphragm 40 secured to one end thereof; a smaller diaphragm 41 is secured to the opposite end of said support. The area within the bonnet 38 forms a chamber 42 which receives the pressure signal from the unit A, this signal acting upon diaphragm 40 and tending to urge the diaphragm assembly in a direction to the left in FIGURE 1. The opposite side of the diaphragm 40 is exposed within a chamber 43 which is provided between the two diaphragms. A controlled pressure is conducted to chamber 43 through a line 44 which has a suitable regulator 45 therein. The pressure in chamber 43 is preselected or predetermined and opposes movement of said diaphragm by the pressure signal transmitted from unit A into chamber 42. By properly adjusting the pressure in chamber 43, the action of the pilot control device B is controlled to thereby actuate the brake lever in a manner to control the weight on the bit.

The smaller diaphragm 41 of the assembly within the device B has one side exposed within a chamberv 46 which is supplied with a pressure through a line 47 connected in the end cap 37. The pressure in chamber 46 may be termed the pilot or control pressure since it is this pressure which controls operation of the motor device D and, therefore, controls movement of brake lever 21. A valve element 48 controls the admission of the pilot pressure into and out of the chamber 46, said element being formed with suitable ball valves 49 and 50 on its extremities. Ball 49 co-acts with an inlet seat and, when disengaged from said seat as illustrated in FIGURE 1, allows entry of pressure from line 47 into the chamber 46.

The ball valve 50 is engageable with a seat at the end of an axial bore 51 formed in the central diaphragm support 39. The opposite end of the bore 51 has communication through a flexible tube 52 with atmosphere. When ball valve 50 is in seated position as shown in FIGURE 1, the bore 51 is closed and pressure from chamber 46 cannot escape to atmosphere and is directed to the line 24; unseating of said ball valve will, of course, vent chamber 46 to atmosphere.

When the diaphragm assembly moves to the right in FIGURE 1, the diaphragm support 39 tends to move away from the ball 50 of valve member 48; however, since said valve member is free floating and pressure from line 47 is acting against the ball 49, such pressure moves the element to cause it to follow the support 39 until the ball 49 of valve element 48 engages the inlet seat. Thereafter, the end of the support 39 of the diaphragm assembly moves away from ball valve 50, thereby opening the bore 51 and permitting the escape of pressure from chamber 46 through said here and outwardly through the flexible tube 52 to atmosphere. It is thus evident that in one position of the diaphragm assembly of the device B, pressure from line 47 may enter the chamber 46; in another position of said diaphragm assembly, chamber 46 is vented to atmosphere.

The pressure in chamber 46 is conducted through line 24 to the pneumatic multiplier unit C. This unit is a typical pneumatic multiplier which is well known in industry and functions as a relay pressure control device. It may be of any desired construction, and its function is to multiply the pressure signal which is conducted through line 24 and to relay or send the increased signal through line 25 to the motor device D. Suitable pressure is supplied to the multiplier unit C through a supply line 25a. By employing the multiplier unit C, a relatively low pressure may be employed in chamber 46 and may be sent to the multiplier device to actuate the same. Upon actuating of said unit, a greater pressure which is suflicient to actuate the motor device or actuator D is trans mitted to said motor device. A suitable hand valve 25b may be connected in line 25.

The operation of the pilot control device B in controlling the operation of the motor device or actuator D, which in turn controls the brake lever 21, is believed obvious from the foregoing. Assuming the parts to be in the position shown in FIGURE 1, a regulated pressure is present in the chamber 43 on one side of the large diaphragm 40, and a pressure which is proportional to the tension in the deadline 11a is present on the other side of said diaphragm. In this position, a pressure is present in chamber. 46, and this pressure has acted upon the multiplier unit C so that the motor device D is subjected to a predetermined pressure.

A decrease in the tension in the deadline 11a will result in the tension responsive unit A sending a decreased pressure signal to chamber 42, which will result in a movement of the diaphragm assembly within the device B in a direction to the right. Such movement will seat valve 49 and will unseat the ball valve 50. Chamber 46 is thus placed in communication with atmosphere to permit pilot pressure from this chamber to be reduced. The pressure reduction acting through line 24 on the multiplier unit C will result in a lesser pressure acting on the motor device D. Such lesser pressure will permit the main spring 22 acting upon the brake lever 21 to move the lever back toward a more fully braking position.

Any subsequent increase in tension in line 11a will move all of the parts in a reverse direction and will result in an upward movement of the brake lever 21 to release braking action and allow some payout of the cable.

The auxiliary control unit which feeds back intelligence from the drum upon the rotation of said drum is clearly shown in FIGURES 2 to 4. The unit E includes a movement detecting wheel 60 which is mounted on the extended end of a main shaft 61. The wheel 60 is adapted to engage the inner surface of the flange 20a of the cable drum and, when in such engagement which is during normal operation of the automatic drilling control apparatus, a rotation of the drum will result in a rotation of the shaft 61. The shaft 61 extends througha cylindrical housing or barrel 62 and is suitably mounted therein on bearings 63. The valve means V is disposed within a bonnet 64 which is threaded onto the end of the housing 62. The housing, shaft and valve means are carried in a block 65, said block being formed with a bore 66 through which the housing or barrel 62 extends; a suitable set screw 67 secures the housing within said block.

The block which supports the housing 62 is, in turn, mounted between the yoke arms 68 of a yoke element 69. Each yoke arm is pivoted at 70 to the block 65, whereby said block may undergo a pivoting movement with respect to the yoke member 69. The yoke member is formed with a depending lug 71 which is adapted to be secured to an upstanding bracket or support 72 by means of a suitable bolt 73. It is evident that the bolt provides a means whereby the yoke member 69 may be secured in various adjusted positions with respect to the fixed support or bracket 72.

As is well known, the usual cable drum 20 is used for various well operations other than suspending the drilling string during actual drilling, as for example, said drum is employed for handling the well pipe. When the drum is 7 being used for other well operations, it is desirable tha the detecting wheel 60 be disengaged from the flange and for this reason, the wheel 60, its shaft 61 and associated parts are mounted in the manner shown.

For efiecting a pivoting movement of the supporting block 65 which carries the housing and shaft assembly to control engagement and disengagement of the detecting wheel 60 with the flange 20a of the cable drum 20, the block 65 is formed with'an extension arm 74 which overlies the yoke member 69. The yoke member carries a pressure actuated diaphragm 75 which is disposed within a suitable diaphragm housing 76' secured to the yoke member. A follower 76 abuts the diaphragm 75 and has its outer end adapted to engage an adjusting screw 77 which is threaded within the extension arm 74. A coil spring 78 confined between the outer surface of the extension arm 74 and a fixed support bar 79 constantly urges the extension arm 74 in a direction toward the yoke member 69 and functions to maintain the end of the screw 77 in contact with the diaphragm follower 76.

Pressure from a suitable source (not shown) is conducted to the diaphragm case 76' through a line 76a in which a manually operated control valve 76b is connected (FIG. 1). With the valve 76b in open position pressure is applied to the diaphragm, and as illustrated in FIGURE 3, the follower 76, engaging screw 77, moves the extension arm 74 against the pressure of the spring 78 to the position shown in FIGURE 3. In such position the extension arm 74 and the block 65, which is secured thereto, have moved the roller 60 on' the rotatable shaft 61 into contact with the flange 20a of the cable drum. When pressure is released from the diaphragm case 76' so that no pressure is acting against diaphragm 75, the spring 78 acting on the outer end of the extension arm 74 moves this end of the arm inwardly with respect to the yoke member 69. Such movement will result in a slight pivoting motion of the block 65, housing 62 and the rotatable shaft 61, whereby the roller or wheel 60 on the outer end of the shaft 61 is disengaged from the drum flange. In this position of the parts the auxiliary unit E is rendered inactive because any rotation of the drum will not be transmitted to the shaft 61; as has been noted, it is desirable to render the auxiliary unit E inactive by disengaging the detecting wheel 60 when the cable drum is being used for well operations other than actual drilling. Although the pressure actuated diaphragm 75 has been found to be a satisfactory way of engaging or disengaging the movement detecting wheel or roller 60 from the drum to activate or deactivate the unit E, it is evident that other means could be employed.

The valve assembly or means V of the unit E is provided for the purpose of venting a portion of the pressure from the line 24, such pressure being the pilot or control pressure acting on the pneumatic multiplier C to control the position of the motor device D. As has been noted, the valve means is mounted within the honnet 64 secured to the end of the housing 62, and this bonnet has its interior forming a chamber 80. The chamber 80 is in communication through the line 33 with the control line 24. A manually adjustable valve 33a may be connected in line 33 and, by proper adjustment, will control the amount of pressure which is released from the system when the valve means V actuates to vent the line 33.

One type of valve means which has been found satisfactory for the present purpose is clearly shown in FIG- URES 3 and 4. This valve means includes a valve block 81 which is confined between the end of the housing or barrel 62 and an internal shoulder 82 formed within the bonnet 64. The rotatable shaft 61 has a reduced portion 61a which projects through a central bore 83 formed in the valve block 81. shaft portion 61a projects into the chamber 80 and has a valve disk 84 keyed or otherwise secured thereto. The

valve disk 84 has its inner surface abutting the face of 75 The outer end of the reduced 8 the valve block 81 and is maintained in contact therewith by means of a coil spring 85. As the shaft 61 is rotated by reason of its wheel or roller 60 engaging the flange of the cable drum 20, the valve disk 84 carried by the reduced end portion 61a of the said shaft is also rotated.

As will be explained, the valve disk is provided with ports and passages which co-act with ports and passages in the valve block 81 to accomplish a venting of the pressure from the chamber 80. As has been noted, the pressure in chamber is the same pressure as that in the line 24 which is the pilot or actuating pressure; therefore, as pressure from chamber 80 is vented, the pressure in line 24 is reduced, and a reaction by the device D due to the reduction of pressure will be effected by reason of release of the pressure in the multiplier device C.

Surrounding the valve block 81 and adapted to be communicated with the chamber 80 are a pair of toroidal chambers. and 87, such chambers being formed by a split housing 88 having a flexible diaphragm 89 clamped between the sections of the said housing. Each chamber 86 and 87 is arranged to alternately communicate with the chamber 80 and with atmosphere, such alternate communication being accomplished by rotation of the valve disk 84 with respect to the valve block 81.

As shown in FIGURE 4 the valve disk, which is secured to the reduced end portion 61a of the control shaft 61, is formed with a plurality of ports 90 which are located at spaced radial positions within the disk. Each port 90 extends completely through said disk, as shown in FIGURE 3. In addition, the inner surface of the valve disk is provided with recesses 91, such recesses being disposed between the ports 90. As illustrated, five ports and five recesses are provided in the disk 84, but the number may be varied as desired. The ports 90 and recesses 91 of the valve disk 84 are arranged to co-act with passages in the valve block 81. With the parts in the position shown in FIGURE 3, one of the annular,

recesses 91 of the valve disk spans the space between an angular passage 92 formed in the valve disk and a longitudinal passage 93 also formed in said disk. The angular passage 92 communicates through a port 94 with the toroidal chamber 86, while the longitudinal passage 93 communicates with a chamber 95 which has a vent passage 96 extending therefrom. When the recess 91 spans the ends of the passages 92 and 93, any pressure within chamber 86 may pass from said chamber through passage 92, recess 91, passage 93 and outwardly through the vent opening 96, whereby pressure from the chamber 86 is vented to atmosphere.

At the same time that one of the recesses 91 is co-acting with the pair of passages 92 and 93, one of the ports 90 in the valve disk is aligned with an angular passage 97 in the valve block; this angular passage (FIGURE 3) communicates with the other toroidal chamber 87 so that a communication is established between the chamber 80 and the chamber 87. The valve block is also formed with a longitudinal passage 98 extending entirely therethrough. With the valve disk in the position shown in FIGURE 3, the passage 98 is inactive, but when the disk is rotated to locate one of the recesses 91 in a position spanning the ends of the passages 97 and 98, said recesses will function to establish communication between the chamber 87 and the vent passage 96, whereby the chamber 87 will be vented to atmosphere.

In describing the action of the valve means V, it will .be assumed that the parts are in the position shown in FIGURE 3, and it will be further assumed that the cable drum is not undergoing any rotation. As this time the pressure in the chamber 80 of the valve means V is the same as the pressure in line 24, which is the pilot or control pressure. This same pressure is also present in the chamber 87 of the valve means V.

Assuming thatthe tension in the deadline changes whereby unit A directs a signal pressure to unit B, such signal results in directing increased pressure to the motor sperms device D in the manner heretofore described. When this occurs the brake lever 21 of the cable drum is moved upwardly against tension of the .spring 22, thereby reducing the braking action and permitting a payout of the cable from the drum. As soon as the drum 20 rotates due to this reduction in braking action, the wheel or roller 60 on the shaft 61 is rotated, and this results in a rotation of the valve disk 84. This rotation moves one of the recesses 91 into position spanning the passages 97 and 98, thereby releasing the pressure from chamber 87 to atmosphere. At the same time one of the ports has moved into alignment with the angular passage 92 in the valve block, so that pressure from chamber 80 may flow into the second toroidal chamber 86. As pressure is withdrawn from chamber 80, it must be replaced from pressure in the line 24, and this results in a reduction in the pilot or control pressure in line 24. Since the control pressure which determines the-position of the brake lever 21 is affected, the pressure acting on multiplier unit C is varied, and the diaphragm motor device or actuator D is immediately moved in a direction which will tend to lower the brake lever21 back toward its original position.

It is thus seen that as soon as the brake lever is slightly released, the auxiliary unit E immediately bleeds off some pressure from the pilot or actuating line to partially de-energize the main control or actuating system.

By arranging the ports and passages in the manner shown,

this bleed-oil of pressure is in volumetric increments. As soon as the cable drum moves, a metered volume of air is immediately exhausted from the primary control or actuating system, and the brake lever is partially returned to its braking position. As illustrated, the valve assembly V effects ten separate volumetric exhaust pulses per revolution of its shaft, but by changing the number and arrangement of ports, any desired number of pulses per revolution may be obtained. It has been found that one or two exhaust pulses are sufiicient to cause the brake lever 21 to return to a controlling position where it has slowed or stopped the paying out of the cable from the drum. By this time the primary actuating system has had sufficient time to reverse itself on a change in signal from the tension responsive unit A. If the pneumatic system is satisfied in accordance with the adjustment of the predetermined pressure as controlled by regulator 45, then no further motion occurs; however, if the system is not satisfied, the pressure is caused to increase at the motor device D, and further paying out of the cable occurs with the auxiliary unit E again counteracting any over-control by the motor device D.

It is pointed out that the auxiliary unit E, while in motion, is actually counteracting the signal to pay out the cable, which signal comes from the differential pilot control B. The auxiliary unit E is in an overriding position being responsive solely to cable payout, and if there is a constant signal from the differential pilot control B to pay out cable, the auxiliary unit acts as a limiting device to limit the maximum rate at which the cable can be fed off, the drum. This feature provides for safety since it will prevent any accidental or sudden dropping of the drill pipe.

Since drilling speeds will vary, it is desirable to provide for adjustment so that either fast or slow drilling can be carried out while still maintaining the necessary control. The valve'33a, which is located in the line 33 extending to the valve means V of the auxiliary unit, provides a simple and efiective adjustment which is made in accordance with actual drilling rates. Where fast drilling is encountered, the valve 33 is adjusted so as to minimize the effect of the auxiliary unit and thereby permit a fast drilling rate. By adjusting the valve in an opposite direction, proper control can be maintained under slow drilling rates. The apparatus thus makes it possible to have a continuous, semi-modulated paying out of drilling cable under fast drilling conditions or to provide a noncontinuous semi-modulated paying out of the cable under slow drilling conditions. The action on the brake handle 21 is smooth and, being responsive to the operation of unit E, its action is substantially immediate. The action is practically the same as expert manual operation except that the auxiliary unit senses the desired changes sooner to .provide extremely efiicient control.

In summarizing the operation, the tension responsive unit A transmits a signal through line 35 which is proportional to the tension in the cable system. This force in the system and in the deadline increases as the drilling bit penetrates the formation. The pressure signal from the tension responsive unit A is applied'to one side of the main diaphragm 40 of the differential pilot control device B. The other side of this diaphragm is resisted by a controlled pressure in chamber 43, which pressure isadjusted by the regulator 45. It is the adjustment of the regulator and of the pressure in chamber 43 which is made manually and which determines the control point, that is, how much weight shall be carried by the derrick.

As is well known, weight on the bit is determined indirectly; the only weight that can be measured is the weight of the drill string on the derrick.

As a practical example, if the drill pipe string at a .given time weights 150,000 lbs. and it is desired to carry 30,000 lbs. of weight on the bit, then the drill pipe will be placed on bottom and slacked off until there is only 120,000 lbs. remaining supported by the derrick. In this assumed instance, the drilling control apparatus will be zeroed" at 120,000 lbs. As the bit drills and penetrates the formation, additional weight is added to the derrick, and this results in increased tension on the deadline 11a. Whenever the weight increases beyond the adjusted point, that is, 120,000 lbs., unit A will provide a signal which will result in paying out some cable. Thus, cable will be fed off at a rate to hold the weight on the derrick at 120,000 lbs.

The signal from unit A which is responsive to tension in the line is transmitted to the differential pilot device B, and said pilot device moves to transmit a pilot or control pressure in the line 24 which is proportional to the weight change. This pressure is directed to the multiplier unit C, and said unit transmits pressure to the motor diaphragm device or actuator D which, in turn, actuates the brake lever 21 through the cable 30.

As the brake lever 21 is moved toward released position, the drum begins to rotate to pay out drilling cable into the fast line section 11b of the cable system. Immediately when the drum begins to rotate and payout of cable begins, the wheel or roller 60 of the auxiliary unit is rotated to rotate the shaft and actuate the valve assembly V of said unit. Since the wheel or roller 60 is relatively small in diameter compared to the diameter of the drum flange 20a, the shaft 61 makes one complete revolution in a relatively small distance of travel of the drum flange. Thus, as soon as the cable drum starts to rotate, the valve assembly V of the auxiliary unit E begins to exhaust pressure from line 24, and this in turn exhausts pressure through the multiplier unit C which is acting upon the motor diaphragm device D to partially de-energize the main actuating system. The exhaust of pressure from the device D results in the movement of the arm 29 and movement of the cable 30 in a direction which permits the brake lever to again move back toward a full braking position. Therefore, the motor device D which controls the brake lever 21 does not have to wait for another signal from unit A before the brake lever is again moved toward more braking action. Through the use of the auxiliary unit B, an immediate response is obtained, and as soon as the drum 20 begins to rotate to pay out cable, the device D is acted upon through the exhaust of pressure by the valve means V; thereafter, further rotation of the drum is slowed down or halted. The use of the auxiliary unit E eliminates the disadvantages of the time lag between the signal'generated by the ten- 11 sion responsive device A and the inherent slowness of reversal of all of the parts in the primary actuating system. With the apparatus shown. the weight-on-bit may be accurately controlled within small limits.

As shown in full lines in FIGURE 1, the valve V associated with'the auxiliary unit E communicates through line 33 with the control or pilot pressure line 24 which connects the differential pilot device B with multiplier unit C. As described above, valve V functions to vent a portion of the pressure from line 24 and, therefore,

affects the multiplier unit C which, in turn, afiects the motor diaphragm device D. However, it is not essential that line 33 be connected to line 24 since it would be possible to communicate line 33 with the conductor 25 in the manner illustrated by the dotted lines 33b in FIG- URE 1. In such case, operation of the valve V due to drum rotation will function to vent the pressure acting upon the motor diaphragm device D. In either construction, the results of the invention are accomplished.

As has been noted, various modifications of the units in the apparatus may be employed, and in FIGURE 6 a modified type of pilot control device B is illustrated. The device B includes a main casing 136 which has a single diaphragm 140 located therein. One side of the diaphragm is exposed within a chamber 142 to the pressure signal which is transmitted by the unit A, the line 35 having communication with said chamber. A chamber 146 which is similar to the chamber 46 of the first form and which contains the modulated pressure is supplied through the line 47. Extending from this chamber is the conductor 24 which extends to the multiplier unit C. A valve 148, similar to the valve 48 of the unit D, is also employed.

In this form of the invention instead of employing a regulated pressure, which is opposing the pressure in chamber 142, an adjustable spring 150 is provided. This spring has one end abutting a cage 151 which is secured to the diaphragm 140. The opposite end of the spring abuts an enlargement 152 on the end of an adjustable stern 153. It will be evident that the spring pressure is acting upon the diaphragm 140 to constantly urge said diaphragm in a direction to the right or against the pressure in chamber 142. By adjusting the stem 153, any desired opposing force can be imparted to diaphragm 140. The operation of this device would be the same as that of the device B, the only difference being that an adjustable spring is substituted for the use of the regulated control pressure in chamber 43.

In the form of valve means V illustrated in FIGURES 2 and 3 and employed with the auxiliary control unit E, the toroidal chambers 86 and 87 are illustrated. However, the use of such chambers is not essential to the operation of the valve means, and in FIGURE 5 a modification of this structure is shown.

In this form, a valve block 181 is substituted for the valve block 81 of the first form. This block is provided with an angular passage 192 and a longitudinal passage 193, the former communicating with an annular recess 194, which is formed in the internal wall of the bonnet 164. The valve block is also provided with passages 197 and 198, with passage 197 also communicating with the annular recess 194 as well as with a port 195 which leads to an enlarged chamber 200. The valve disk 84 is employed with this modified valve block and functions to establish communication alternately with the two series of passages so as to alternately communicate the chamber 80 with the chamber 200 or to communicate said chamber with the vent passage or opening 96.

The operation of the valve means in FIGURE 5 is substantially the same as that heretofore described with reference to the operation of the form shown in FIGURE 3. The only difference in these two structures is that pressure from chamber 80 is directed into the storage chamber 200 instead of being directed into one or the other of chambers 86 and 81. When communication is established between chamber 200, as illustrated in FIG- URE 5, the passages 192 and 193 are inactive. However, when recess 91 in valve disk 84 spans passages 197 and 198, a portion of the pressure in chamber 200 is vented to atmosphere. The valve disk 84 in the form of FIG- URE 5 is actuated by the rotatable shaft 61 which is responsive to rotation of the cable drum.

It is not essential that the valve means V be mounted in the manner illustrated in FIGURES 1 and 2, and neither is it essential that the particular auxiliary unit E be employed. The important feature of the present invention is to provide some means which is responsive to the cable drum movement and therefore to the cable payout to feed back intelligence to the primary system so that the motor device D may react immediately after initially actuating the brake lever 21. In FIGURE 7, a modification of the system is illustrated showing another type of auxiliary unit which would be satisfactory.

In this form of the invention, a rotatable shaft 161 having a wheel engageable with the drum flange 20a is employed to actuate a hydraulic pump 201. The pump is connected with a reservoir 202 and with proper piping which communicates the output of said pump with a motor valve 203. The motor valve actuates a valve element 204 which is connected in the line 33 extending from the main actuating line 24. When the pump 201 is actuated by rotation of shaft 161 and builds up its output pressure, such output is directed against the diaphragm of motor valve 203 causing valve 204 to be opened. Upon unseating of valve 204, a portion of the pressure from line 33 is vented through a discharge opening 205 to atmosphere. The venting of this pressure will reduce the modulated or controlled pressure in line 24 and cause a reaction on the motor device D which will return the brake lever 21 toward its initial position.

Another form of auxiliary control is illustrated in FIGURE 8 which shows a remote control which is responsive to drum rotation. As shown in this figure, a control shaft 261, which is rotated by 'means of a movement detecting wheel or roller 260, may actuate a Selsyn motor 262. This motor, in turn, drives a remotely located Selsyn motor 263, and the latter may be utilized to rotate the shaft which carries the valve disk 84 of the valve means shown in FIGURE 5. The valve means would, of course, be connected in the line 33 which communicates with the modulated or primary control pressure in line 24. With the arrangement of FIGURE 8, the valve meansv and its Selsyn motor 263 may be located at any point remote from the cable drum. However, the operation and the accurate and sensitive control of the cable drum may still be obtained.

In the preferred embodiment of the invention as illustrated in FIGURE 1, the pneumatic multiplier unit C is employed. However, the device C is not essential to the operation of the system but is used to improve the sensitivity. By providing a larger and greater signal-producing pilot control device B, it is possible to completely eliminate the use of the multiplier unit C, in which event the line 24 from the pilot control device B would extend directly to the device D.

The foregoing disclosure and description of the invention is illustrative and explanatory thereof, and various changes in the size, shape and materials, as well as in the details of the illustrated construction, may be made within the scope of the appended claims without departing from the spirit of the invention.

What we claim is:

1. A drilling control apparatus for controlling a rotatable cable drum for paying out cable into a cable system which is in tension including, a rotatable cable drum having the cable wound thereon, braking means acting upon said cable drum, an actuator for controlling the braking means, means responsive to tension in the cable system and including fluid means for energizing and dcenergim'ng the actuator to control the braking means and and unaffected by the actuator and its energizing means,

whereby the discharge passage is opened when cable payout occurs'to partially reduce the effect of said actuator upon the braking means.

2. A drilling control apparatus for controlling a rotatable cable drum for paying out cable into a cable system which is in tension including, a rotatable cable drum having the cable wound thereon, braking means acting upon said cable drum, a pneumatic actuating system responsive to the tension in the cable system and including an actuator having connection with the braking means for controlling said braking means to thereby control cable payout, pressure energization of said pneumatic actuating system operating its actuator to move the braking means in a direction which releases the cable drum for rotation to pay out cable, and an auxiliary control unit including a part having a discharge passage in communication with the pneumatic actuating system and a part which is movable with respect to said discharge passage to periodically open and close the passage, the

pressure in said pneumatic actuating system being partially reduced to partially de-energize the actuator each time the passage is opened, said auxiliary control unit also including operating means operatively connected to said movable part and responsive solely to the payout of cable from the cable drum and unaflected by the actuating system, whereby the discharge passage is opened when cable payout occurs to partially reduce of the actuator upon the braking means.

3. A drilling control apparatus as set forth in claim 1, wherein the operating means of the auxiliary control unit is responsive to cable payout by the engagement of said operating means with the cable drum, and means connected with said operating means for disengaging it from the drum to render said auxiliary unit inactive.

4. In combination, apparatus for controlling the weight applied to a drill bit assembly suspended from a traveling block which is, in turn, suspended from a crown block by a cable system having a dead line section and having a fast line section extending from a cable drum provided with braking means for paying out cable from said cable drum into the fast line section of the cable system, a pressure-operated actuating system responsive to and energized by the tension in the dead line section of the cable system and having connection with the vbraking means for controlling said braking means to control drum rotation as caused by the weight of the drill bit assembly to thereby control paying out of the cable into the cable system, energization of the pressure-operated actuating system operating the braking means to allow drum rotation in a direction to pay out cable and de-energization of said system operating said braking means in a direc tion to reduce the rate of payout of the cable, and an auxiliary control unit including a valve means comprising a part having a discharge passage in communication with the actuating system and a part movable with respect to said passage to periodically open and close the passage, the actuating system being partially de-energized each time said passage is opened, said auxiliary control unit also including operating means connected to the movable part of said valve means and responsive solely to payout of cable from the cable drum and being unaffected by the actuating system, whereby the discharge passage is opened following the payout of cable to partially reduce the effect of the actuating system upon the braking means.

the etfect 5. The combination set forth in claim 4, wherein the actuating system is a pneumatic system and also wherein the auxiliary control unit includes means for venting a controlled volume of air from said system each time that the discharge'passagis opened.

6. The combination as set forth in claim 4, wherein the operating means for the auxiliary control unit is in direct engagement with the cable drum whereby rotation of the drum operates the valve means of said control unit, and means mounting said operating means for movement relative to the drum to permit said operating means to be selectively disengaged from the drum and thereby render the auxiliary control unit inactive.

7. A drilling control apparatus as set forth in claim cumferentially spaced vent openings which periodically register with the discharge passage to open the passage and thereby effect a predetermined incremental release of pressure from the pneumatic actuating system as said venting valve is rotated.

8. A drilling control apparatus for controlling a rotatable cable drum for paying out cable into a cable system which is in tension including, a rotatable cable drum havingthe cable wound thereon, braking means associated with and acting upon said cable drum to control rotation of the drum as caused by the tension in the cable system, a pressure-actuated power means connected with said braking means, means responsive to the tension in the cable for controlling the application and release of an actuating pressure to and from the power means, application of said actuating pressure to the power means operating the braking means to release the drum for rotation in a direction to pay out cable from the drum and release of the actuating pressure from said power means operating said braking means in a direction to reduce or halt the paying out of cable from said drum, and an auxiliary unit including an immovable discharge passage in communication with the actuating pressure and also including a valve member movable with respect to the discharge passage for opening and closing said passage, opening of said discharge passage venting a portion of said actuating pressure to partially reduce the pressure acting on the power means, said auxiliary unit also including an operating element for the valve member which element has operative connection with the cable drum and is responsive solely to the rotation of said cable drum, whereby opening of the discharge passage by said valve member of said auxiliary unit is controlled solely by the rotation of the cable drum. 9. A drilling control apparatus for controlling a rotatable cable drum for paying out cable into a cable system which is in tension including a rotatable cable drum having the cable wound thereon, braking means associated with and acting upon said cable drum to control the rotation of the drum as caused by the tension in the cable system, a pressure actuated power means connected with the braking means, a conductor for conducting an actuating pressure to said power means, a relay pressure control device in said conductor for applying actuating pressure to the power means, means responsive to the tension in the cable system for operating the relay pressure control device in accordance with variations in tension in said cable system, whereby the power means is actuated to pay out cable from the drum or to reduce or halt such paying out in accordance with the tension in the cable system, an auxiliary pressure-venting unit in communication with the relay pressure control device at a point between said relay pressure control device and the means responsive to the tension in the cable system, said auxiliary unit including a discharge passage and a valve member movable with respect to said passage for opening and closing said passage and also including an operating element for imparting movement to the valve member, said operating element having operative connection with the cable drum whereby the opening and closing of the discharge passage is controlled solely in accordance with the rotation of said cable drum.

10. A drilling control apparatus for controlling a rotatable cable drum for paying out cable into a cable system which is in tension including a rotatable cable drum having the cable wound thereon, braking means associated with and acting upon said cable drum to control rotation of the drum as caused by tension in the cable system, a pressure-actuated power means connected with the braking means, a conductor for conducting an actuating pressure to said power means, a relay pressure con trol device in said conductor for applying actuating pressure to the power means, means responsive to the tension in the cable system for operating the relay pressure control device in accordance with variations in tension in said cable system, whereby the power means is actuated to operate the braking means to pay out cable from the drum or to reduce or halt such paying out in accordance with the tension in the cable system, an auxiliary pressure venting unit in communication with the conductor for conducting pressure to the power means and having a connection to said power means at a point between the power means and the relay pressure control.

device, said auxiliary unit including a discharge passage and a valve member movable with respect to the passage for opening and closing said passage and also including an operating element for imparting movement to the valve member, said operating element having operative connection with the cable drum whereby .the opening and closing of the discharge passage is controlled solely in accordance with the rotation of said drum.

11. A drilling control apparatus for controlling a rotatable cable drum for paying out cable into a cable system which is in tension including, a rotatable cable drum having a cable wound thereon, braking means associated with and acting upon said cable drum to control rotation of the drum as caused by tension in the cable system, a pressure-actuated power means connected with the braking means, a conductor for conducting an actuating pressure to said power means, a pilot pressure con.-

trol device in said conductor for either directing actuating pressure to the power means or releasing pressure from said power means, means responsive to the tension in the cable system for operating the pressure control device in accordance with variations in tension in said cable system, whereby the power means is actuated to operate the braking means to pay out cable from the drum or to reduce or halt such paying out in accordance with the tension in the cable system, an auxiliary pressure-venting unit in communication with the conductor at a point between the pilot pressure control device and the power means for conducting pressure to the power means, said auxiliary unit including a discharge passage and a valve member movable with respect to the passage for opening and closing said passage and also including an operating element for imparting movement to the valve member, said operating element having operative connection with the cable drum whereby the opening and closing of the discharge passage is controlled solely in accordance with the rotation of said drum.

12. A drilling control apparatus as set forth in claim 11, wherein the valve member of the auxiliary pressure venting unit comprises a rotatable venting valve disk having radially spaced vent openings, said valve disk being located adjacent the discharge passage so that periodic registration of the vent openings with said passage opens said passage which produces a pressure reduction in the system each time the passage is opened as said venting valve disk is rotated.

References Cited in the tile of this patent UNITED STATES PATENTS 2,657,011 Slonneger' Oct. 27, 1953 2,783,968 Bell Mar. 5, 1957 2,950,086 Abraham Aug. 23, 1960 FOREIGN PATENTS 776,132 Great Britain June 5, 1957 OTHER REFERENCES The Oil and Gas Journal," volume 56, No. 49, Dec. 8, 1958, page 125.

Disclaimer 3,031,169.A1"t I Robinson, Vichita Falls, Tex., and Garnum O. Kimnwll, Oklahoma City, Okla. APPARATUS FOR AUTOMATICALLY CONTROLLING DRILLING. Patent dated Apr. 24, 1962. Disclaimer filed Dec. 22, 1966, by the assignee, Bear Manufactufimg Uarporation. Hereby enters this disclaimer to claim 9 of said patent.

[Ofiicial Gazette F ebruary 14, 1967.] 

